1) Field of the Invention
The field of this invention relates to hand tools and more particularly to a hand tool for applying rotational force to an object such as a torsion spring.
2) Description of the Prior Art
Overhead doors are in common use. The most common area of usage for an overhead door is for a garage in a home and for a warehouse in a place of business. The garage and the warehouse utilize an enlarged access opening. This access opening is to be closeable through the use of an overhead door. The overhead door is capable of being raised to assume a raised position providing unobstructed access through the access opening.
In order to raise the overhead door, it is necessary to lift the weight of the door. Lifting the weight either manually or by an automatic door opener would normally take a substantial amount of force as such overhead doors can weigh as much as several hundred pounds. In order to provide for ease of raising of an overhead door, it is common to incorporate a counterbalancing mechanism in conjunction with the door. One common form of such a counterbalancing mechanism utilizes a torsion spring. A length of torsion spring which is mounted with a winding cone on each end and this assembly is mounted around a rotatable horizontal shaft. One end of the spring is fixedly secured to the frame of a garage or warehouse. The other end of the spring is fixed onto a winding cone which is fixedly secured to the torsion shaft that runs through the torsion spring. A cable drum is fastened to the torsion shaft and a length of cable extends from the drum to the overhead door. As the door is lowered, cable is rolled from the drum, rotating the shaft and placing the spring in torsion, thus storing part of the potential energy due to the weight of the door. In elevating of the door, the spring exerts an upward force transmitted through the torsion shaft, drum and cable to assist in raising the door, counterbalancing the weight of the door, thus reducing the exterior force that is required in order to lift the overhead door. Normally the amount of spring force that is emitted is just slightly less than the amount of force that is required to lift the door. This means that the normal at rest position of the door is in the position closing the access opening. However, upon application of a slight lifting force to the door, the door will then proceed to move to its open position.
It is to be understood that although the subject matter of this invention has found particular utility in conjunction with overhead doors, it is considered to be within the scope of this invention that it could be used with other structure, but not limited to, closures such as an awning and a gate.
During installation of the door or during replacement of a defective spring, it is necessary to wind the spring to provide the desired amount of potential energy. The winding of the spring in the past has been accomplished by using a pair of rods which are inserted within holes provided within the winding cone of the torsion spring apparatus. One of the bars when inserted in conjunction with the winding cone is to be lifted to pivot as much as 50 or 60 degrees. Then a second bar is inserted within a similar opening provided within the winding cone and force is applied to that bar pivoting of the winding cone again another 50 or 60 degrees with the first bar having been removed from the winding cone. This sequential winding type procedure is continued until the desired amount of potential energy is achieved within the torsion spring. The disadvantage of this technique is that it is exceedingly common for these bars to slip free from the hole provided within the winding cone. The result is the bar can be propelled in an undesirable direction and it is exceedingly common that installers can be injured by such a bar. Also, some times the force is so great that a rod may be bent which may cause the rod to slip out of its position again causing the energy to be quickly released from the torsion spring and capable of causing injury.
In the past it has been attempted to design wrenches particularly for winding of the torsion springs of overhead doors. However, these wrenches of the prior art tend to be complicated devices which are not easily installable in position and because of their complexity are expensive to manufacture.